Performance of DOM/SAXSource vs. StreamSource & other optimization questions

["Karr, David" <da...@wamu.net>]

I haven't tried any of this yet, but I'm investigating options for
optimizing XSLT.  Caching the Transformer object is attractive, but
synchronization issues will make this less attractive.  I'm looking at
implementing this in a messaging router, which could concievably be
attempting the same conversion on 10 different threads at about the same
time, and doing that many thousands of times in a day.

I'm wondering instead about caching a Source object.  Is it practical to
do this?  What about caching a DOMSource or SAXSource instead?  I would
guess that would be better than a plain StreamSource object.  None of
these classes say they are NOT thread-safe, so I assume they are ok with
concurrent references (although I find that a little hard to believe).

This would be implemented with JDK 1.4.2.  Would the "Source" features
be enabled in the stock JAXP implementation in that version?

What does the "optimize" attribute in Xalan do?  Is that available in
the stock JAXP implementation?